Display devices comprising touch-screen functionality in particular are used in mobile communications devices, tablet PCs and navigation devices and form an interface that enables an user to perform input operations by a selective contact with the display device, wherein these input operations typically are accompanied by a user interface visualized by the display device.
Also in conventional display systems, as for example in computer displays, an implemented touch-screen function may offer appealing possibilities of interaction in order to coordinate hereby for example menu selections, cursor movements or image movements as for example the rotation of 3D objects displayed on the display system.
It is known from several patent applications of the applicant, in particular from DE 10 2009 030 495 A1 to design a display device such that besides a touch-screen function it also allows for the detection of the finger of a user before it contacts the display device. In order to also allow the detection of a position of a finger in an area in front of the display device in addition to the contact of the display also specific separate electrodes are provided in addition to the electrode system serving the contact detection which allow to detect changes of the electric properties or states in an area in front of the display device and to derive signals therefrom which allow for a relatively high resolution position detection of the finger of a user. The electrodes serving the contact detection and the electrodes for contactless position detection provided separately therefrom may be enabled consecutively by a time division multiplexer device.